package ZuoYe.java;

public class Yuan2 {
	int r;

	public double mianji() {
		double a = 3.14 * r * r;
		return a;

	}

	public static void main(String[] args) {
		Yuan2 b = new Yuan2();
		b.r = 3;
		System.out.println(b.mianji());

	}
}
